Dewaxing of lubricating oil



Patented Nov. 17, 1936 UNITED STATES nuwaxusc OF LUBRICATING on.

Francis X. Govers, Vincennes, Ind., assignor to Indian Refining Company, Lawrenceville, 111.,

a corporation of Maine No Drawing. Application February 20, 1934, Serial No. 712,172

9 Claims.

This invention relates to the manufacture of lubricating oil from hydrocarbon oils, and more particularly to the manufacture of low pour test lubricating oil from wax-bearing mineral oils.

The present application is a continuation-inpart of my pending application, Serial No. 568,529, filed October 12, 1931, for Dewaxing of lubricating oils.

Broadly, the invention contemplates an improved process of manufacturing low pour test lubricating oil from wax-bearing hydrocarbon oil wherein the oil is mixed with a selective solvent liquid mixture which remains homogeneous and completely miscible with the liquid hydrocarbons at temperatures below 0 F., and which exerts substantially complete solvent action upon the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons at such tem-' peratures. The mixture of oil and solvent liquid is then cooled to precipitate the wax constituents which are removed from the cold mixture in solid form.

In United States Patent No. 1,802,942 issued to me on April 28, 1931, for Process for the recovcry and purification of lubricating oils from mineral oils, I have described a process wherein a selective solvent liquid is used to effect separation of the wax constituents from the oil. A selective solvent as defined therein is a liquid which at temperatures of approximately F. has substantially complete solvent action on a min-' eral oil wax distillate substantially free from constituents having a boiling point equal to or below that of gas oil, and at temperatures of 5 F. and below has substantially complete solvent action on the liquid hydrocarbons therein but substantially no solvent action on the solid hydrocarbons therein and of such a nature that upon cooling a solution of such mineral oil wax distillate in the solvent liquid to 0 F. and removing the solid hydrocarbons so precipitated and the solvent liquid the resulting oil hasa cold test of substantially 0 F.

In some instances, as when dewaxing oil containing relatively large amounts of wax, it may be desirable to adjust the proportions of the components of the solvent liquid mixture such that it is necessary to heat the mixture to temperatures above 100 F. to effect complete solution, so that at temperatures of 0 F. and below the solvent mixture will have the desired selective action as between wax and oil. For example, a solvent mixture having the desired selective solvent action at the dewaxing temperatures, when mixed with a viscous residual fraction of paraffin or semiparaffin base crude oil in which the wax is concentrated, may have complete solubility for such wax-bearing oil at temperatures of around F.

Mypresent invention contemplates a process using a solvent having the foregoing characteristics in addition to certain other desirable properties as herein described.

More specifically the invention contemplates a process of manufacturing low pour test lubricating oil wherein a wax distillate fraction of a mineral oil is mixed with a solvent liquid mixture composed of methyl ethyl ketone in admixture with a solvent liquid such as toluol, characterized by forming with the ketone a mixture which remains homogeneous and completely miscible with the liquid hydrocarbons at temperatures down to 45 F. and below. The resulting mixture is then cooled to a temperature at which substantially all of the wax constituents are precipitated as solid hydrocarbons, and the cold mixture is then subjected to filtration to remove the precipitated solid hydrocarbons.

I have discovered that a solvent liquid mixture composed of methyl ethyl ketone in admixture with toluol, xylol, or cumene, possesses many desirable characteristics. Solvent mixtures of methyl ethyl ketone and toluol, for example, when mixed in proper proportions with each other and with the hydrocarbon oil undergoing treatment, exert, at temperatures below 0 F., substantially no solvent action on the solid hydrocarbons but substantially complete solvent action upon the liquid hydrocarbons. Inaddition, such a solvent liquid mixture remains stable and homogeneous at temperatures even of the order of 40 F. and lower since there is no separation of either of its components from the solution. It remains completely miscible with the liquid hydrocarbons at these low temperatures and, therefore, continues to exert a substantially complete solvent action thereupon even at very low temperatures.

I have found that mixtures of the above solvents are, therefore, very well adapted for use in the removal of wax from paraffin containing oil for the manufacture of a high grade of lubricating oil having a relatively low pour or cold test. Furthermore, these solvent mixtures are particularly well adapted for the manufacture of lubricating oils of 75 Saybolt universal seconds viscosity or above with cold tests below 20 F. from very viscous wax-bearing fractions and which are diflicultly miscible with ordinary solvent mixtures at the low temperatures prevailing during re moval of the wax.

By way of example, when dewaxing a waxbearing lubricating oil distillate having a viscosity of about 80 Saybolt universal seconds at 210 F., about 1 part of the oil is mixed with 4 parts of a selective solvent liquid composed of equal parts of methyl ethyl ketone and toluol. The resulting mixture is then chilled to around 40 F. to precipitate the wax constituents as solid hydrocarbons. The cold mixture is then subjected to filtration to separate the solid hydrocarbons. The solvent is then evaporated and the resulting lubricating oil will have a pour test of around 30 F.

The proportion of methyl ethyl ketone to toluol may be either less or greater than that described above although the methyl ethyl ketone will usually comprise from about 25% to 50% of the methyl ethyl ketone-toluol mixture. Also, the proportion of mixed solvent to wax-bearing oil may vary from that set forth in the above example, and depending upon the nature of the oil it may be desirable to employ, for example, two or three parts of solvent mixture to one part of wax-bearing oil.

While the use of the foregoing solvent liquid mixtures has been described in connection with a lubricating distillate fraction, it is contemplated that they may be used for removing wax from various types of wax-bearing hydrocarbons and that they may be equally well employed with oils of various viscosity ranges, including viscous residual fractions of paraiiin or semi-paraflin base crude oil.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim:

1. The process of manufacturing a low cold test lubricating oil which comprises mixing a waxbearing fraction of a mineral oil with methyl ethyl ketone and toluol in such a ratio to each other and to the said fraction that the methyl ethyl ketone and toluol together at temperatures of approximately 100 F. have substantially complete solvent action on such fraction and at temperatures of 5 F. and below have substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons in said fraction, and upon removal of the solid hydrocarbons and the methyl ethyl ketone and toluol such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of 0 F. or below, and removing therefrom the hydrocarbons so precipitated.

2. The process of manufacturing a low cold test lubricating oil from a wax-bearing fraction of a mineral oil which is substantially free from constituents having a boiling point equal to or below that of gas oil which comprises mixing the said fraction with a solvent liquid composed of methyl ethyl ketone in admixture with a solvent liquid selected from the group consisting of toluol, xylol and cumene in such a ratio to each other and to the said fraction that at temperatures of approximately F. the solvent mixture has substantially complete solvent action on such fraction, and at temperatures of 5 F. and below has substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons therein, and upon removal of the solid hydrocarbons and the solvent liquid mixture such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of 0 F. or below, and removing therefrom the hydrocarbons so precipitated.

3. The processof manufacturing a low cold test lubricating oil from a wax-bearing fraction of a mineral oil which is substantially free from constituents having a boiling point equal to or below that of gas oil which comprises mixing the said fraction with a solvent liquid composed of methyl ethyl ketone in admixture with xylol in such a ratio to each other and to the said fraction that at temperatures of approximately 100 F. the solvent mixture has substantially complete solvent action on such fraction, and at temperatures of 5 F. and below has substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons therein, and upon removal of the solid hydrocarbons and the solvent liquid mixture such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of 0 F. or below, and removing therefrom the hydrocarbons so precipitated.

4. The process of manufacturing a low cold test lubricating oil from a wax-bearing fraction of a mineral oil which is substantially free from constituents having a boiling point equal to or below that of gas oil which comprises mixing the said fraction with a solvent liquid composed of methyl ethyl ketone in admixture with cumene in such a ratio to each other and to the said fraction that at temperatures of approximately 100 F. the solvent mixture has substantially complete solvent action on such fraction, and at temperatures of 5 F. and below has substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons therein, and upon removal of the solid hydrocarbons and the solvent liquid mixture such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of 0 F. or below, and removing therefrom the hydrocarbons so precipitated.

5. A process of manufacturing a low cold test lubricating oil from a wax-bearing fraction of a mineral oil which is substantially free from constituents having a boiling point equal to or below that of gas oil which comprises mixing the said fraction with a solvent liquid composed of about equal parts of methyl ethyl ketone and toluol, chilling the mixture to about 0 F. or below to precipitate the wax constituents, separating the wax thus precipitated, and recovering the solvent from the dewaxed oil.

6. The process of manufacturing a low cold test lubricating oil which comprises mixing a wax-bearing fraction of a mineral oil with methyl ethyl ketone and toluol in such a ratio to each other and to the said fraction that the methyl ethyl ketone and toluol together at temperatures of approximately F. have substantially complete solvent action on such fraction and. at temperatures of -5 F. and below have substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons in said fraction, and upon removal of the solid hydrocarbons and the methyl ethyl ketone and toluol such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of F. or below, and removing therefrom the hydrocarbons so precipitated.

7. The process of manufacturing a low cold test lubricating oil from a wax-bearing fraction of a mineral oil which is substantially free from constituents having a boiling point equal to or below that of gas oil which comprises mixing the said fraction with a solvent liquid composed of methyl ethyl ketone in admixture with a solvent liquid selected from the group consisting of toluol,

xylol and cumene, in such a ratio to each other and to the said fraction that at temperatures of approximately 125 F. the solvent mixture has substantially complete solvent action on such fraction, and at temperatures of F. and below has substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons therein, and upon removal of the solid hydrocarbons and the solvent liquid mixture such fraction has a cold test substantially the same as the temperature of the mixture at the time of the removal of the solid hydrocarbons, cooling the mixture to a temperature of 0 F. or below, and removing therefrom the hydrocarbons so precipitated.

8. The process of manufacturing a low cold test lubricating oil from a wax-bearing fraction of mineral oil which comprises mixing with said fraction a solvent mixture composed of methyl ethyl ketone and toluol in which the methyl ethyl ketone comprises from about 25% to about 50% of the solvent liquid mixture, said mixture being mixed with the fraction in such ratio that at temperatures of 0 F. and below the mixture has substantially complete solvent action on the liquid hydrocarbons but substantially no solvent action on the solid hydrocarbons in said fraction, cooling the mixture to a temperature of 0 F. or below, and removing therefrom the hydrocarbons so precipitated.

9. A process of manufacturing low cold test lubricating oil from a wax-bearing fraction of a mineral oil having a Saybolt universal viscosity of 75 seconds and above at 210 F. and which is substantially free from constituents having a boiling point equal to or below that of gas oil which comprises mixing about one volume of said fraction with up to four volumes of a solvent liquid composed of 25 to 50% methyl ethyl ketone in admixture with 75 to 50% of an oil solvent comprising an aromatic hydrocarbon of the character of toluol, chilling the mixture of solvents and wax-bearing oil to temperatures of 0 F. and below to precipitate the wax, separating the wax thus precipitated, and recovering the solvents from the dewaxed oil.

FRANCIS X. GOVERS. 

